Long Range and Low Powered RFID Tags with Tunnel Diode F. Amato, C. - PowerPoint PPT Presentation

Long Range and Low Powered RFID Tags with Tunnel Diode F. Amato, C. W. Peterson, M. B. Akbar, G. D. Durgin School of Electrical and Computer Engineering Georgia Institute of Technology This work was supported, in part, by NSF Grant ECCS #1408464 1

What if we had a long range RFID tag? 2

Reflection amplifiers 1 2 > 1 M = 0.25 M = 1 M > 1 Reflection amplifiers are active devices that, when properly biased, display a negative resistance (-R). 3

Key accomplishments • Sensitivity to impinging RF signals as low as -90 dBm at 5.8 GHz • Amplification gain of 40 dB with a biasing power of only 29 μW. • The tag implements On-Off keying with Manchester encoding • A range of 22.3 m has been achieved and tested and higher ranges are possible. 4

Performances 44 State of the art for reflection amplifiers This work: tunnel diode-based reflection amplifiers 41 38 35 Dalman72 32 29 Gain [dB] 26 23 20 17 Cantu2006 Chan2013 14 Chan2011 11 Cantu2008 8 Kimionis2014 Lazaro2013 5 10 -2 10 -1 10 0 10 1 10 2 10 3 Bias Power [mW] 5

Quantum tunneling Tunnel Diode IV curve Tunnel Diode IV curve 0.6 0.5 0.4 0.3 0.2 I [mA] 0.1 I [mA] 0 -0.1 -0.2 > 1 -0.3 -0.4 -0.5 -0.6 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 V [V] V [V] 6

Summary of previous results 170 120 70 s 11 phase [deg] 20 -30 -80 -130 Tunnel diode with 0 V bias Tunnel diode with 80 mV bias -180 5 5.2 5.4 5.6 5.8 6 Freq [GHz] A 45 μ W Bias Power, 34 dB Gain Reflection Amplifier Exploiting the Tunneling Effect for RFID applications. Amato, Peterson, Degnan, Durgin. RFID Conference 2015, San Diego. 7

A new RFID tag paradigm Demodulator RF in Charge Pump or Battery DC block modulated RFchoke RF out DC bias tunnel diode Microcontroller Reflection Amplifier Power Power f m f c f c f ls f us Frequ ency Frequ ency a) b) 8

Improvements to our previous design Tunnel diode Model Bias Tee MBD5057-E28, by Cobham Metelics C 1 V Bias Tuning stub RF in Tunnel Diode 9

Improvements to our previous design BiasTee C 1 s V Bi a Tun ing st u b RF in Tun n el Dio de • Used bias powers: 29 μW • Input frequencies: 5.8 GHz 10

45 Improvements 40 35 30 BiasTee M [dB] 25 C 1 20 s V Bi a Tun ing st u b 15 RF in Tun n el Dio de 10 5 0 -100 -90 -80 -70 -60 -50 -40 -30 P in [dBm] • Used bias powers: 29 μW • Input frequencies: 5.8 GHz • Max gain: 43 dB @ -94 dBm of RF input power resulting in very high sensitivity 11

Modulation 12

Modulation P in = -60 dBm f = 5.8 GHz 13

Modulation P in = -60 dBm f = 5.8 GHz 5.8 I - channel Q - channel Amplitude - [mV] 1.8 -2.2 -6.2 0.4002 0.4002 0.4003 t [s] f m = 250 kHz 14

Modulation P in = -60 dBm f = 5.8 GHz 5.8 I - channel Q - channel f m = 1.25 MHz Amplitude - [mV] 1.8 5.8 I - channel Q - channel -2.2 Amplitude - [mV] 1.8 -6.2 0.4002 0.4002 0.4003 t [s] -2.2 f m = 250 kHz -6.2 0.4002 0.4002 0.4003 t [s] 15

Modulation P in = -60 dBm f = 5.8 GHz 0xA4 16

Wireless Backscattering Forward link • EIRP: -14 dBm, r F = 7m • P t = -73 dBm, Pout = - 55dBm/-80 dBm 17

Square wav e generator Tag Wireless Backscattering 23.3 m Backward link Tx/Rx Ant Sig. Gen. + Spec. Analy zer • PT = -20 dBm • GT = Gt = 6 dB • fm = 250 kHz, rF = 23.3 m • M = 38 dB 18

Comparison with an ideal semi-passive tag -60 Range of tag prototype Range of ideal semi-passive tag -70 Reader sensitivity [2] -80 -90 [dBm] -100 min P R -110 -120 -130 -140 1 2 3 4 10 10 10 10 Range [m] 19

Conclusions High communication ranges and long lasting power supplies are possible thanks to: • High reflection gains (above 40 dB) • Low power consumption (29 μW) • High sensitivity: (-90 dBm) 44 State of the art for reflection amplifiers This work: tunnel diode-based reflection amplifiers 41 38 35 Dalman72 32 29 Gain [dB] Technology Power Distances 26 Consumption 23 20 Tdiode tag Cantu2006 29 μ W 480 m to 4 km 17 Chan2013 (semi-passive) Chan2011 14 Cantu2008 11 BLE (active) 33.3 μ W 150 m 8 Kimionis2014 Lazaro2013 802.11n (active) 100 mW 200 m 5 20 -2 -1 0 1 2 3 10 10 10 10 10 10 Bias Power [mW]

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Extra slides 22

Semiconductors I V Energy band diagram, diode 23

Degenerate Semiconductors Tunnel Diode When a p-n junction is formed, a Semiconductors heavily doped with thin junction region is created as donors (n-type) have the Fermi result of keeping the continuity of level up inside the conduction band the Fermi level Semiconductors heavily doped with acceptors (p-type), have the Fermi level inside the valence band I This results in a finite probability that electrons overcome the energy barrier when a small V biasing voltage is applied ( quantum tunneling [3]) 24

The design Aeroflex Metelics MBD5057-E28 Tunnel diode equivalent circuit 25

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Reflection Amplifier Characterization (1/2) Vector Analyzer • Optimum bias voltage: 80 mV • Measured current: 566 μ A • P bias = 45.28 μ W 27

Reflection Amplifier Characterization (1/2) Vector Analyzer • Optimum bias voltage: 90 mV • Measured current: 525 μ A • P bias = 47.25 μ W 28

Reflection Amplifier Characterization (1/2) Vector Analyzer • Δφ 1 = 45 ˚ • Δφ 2 = 53 ˚ 29

Reflection Amplifier Characterization (2/2) • At what RF input power levels is the gain available? • What is the bandwidth of the reflection amplifier? • How does the gain change with bias voltages? Reflection Amplifier • Sig. Gen. E8247C • Sig. An. CXA-N9000A Signal • Res BW: 3 kHz Generator • Video BW: 100 kHz • Span: 1 MHz • Avg: 10 Signal • Points: 1001 Attenuators Analyzer 30

Reflection Amplifier Characterization (2/2) Reflection Amplifier Signal Generator Signal Analyzer • Used bias powers: 45 μW and 47 μW • Max gains: 34.4 dB and 22.1 dB • Input frequencies: 5.45 GHz, 5.55 GHz 31

Reflection Amplifier Characterization (2/2) Reflection Amplifier Signal Generator Signal Analyzer • Used bias voltages: 80 and 90 mV • Input powers: -70 dBm and -60 dBm 32

Reflection Amplifier Characterization (2/2) Reflection Amplifier Signal Generator Signal Analyzer • Input frequencies: 5.45 GHz and 5.55 GHz • Input powers: -70 dBm and -60 dBm 33